Ok I have an '87 4Runner, it's an automatic. When I accelerate up into the 2500-3000 range it seems I have a "dead spot." She will get up to about 2800rpm and then dip down to ~2500rpm and then accelerate again. It also seems like it happens if im like pulling a hill and upshift, at like 3200 rpm it will dip down to 3000 and then get back going again, but like I said it only happens in this range when i upshift and get on the throttle hard. So is this just one of the quirks of the 22re? I havn't had a chance to take a look at anything and I won't for another few days, but does anyone have any ideas? I'm still getting about 21-22 mpg.

 

check your cap & rotor & wires

 

This is a total guess, but maybe your TPS has a burnt spot.

When you reach it, the throttle signal blanks for a second, then figures out where it is once past that point. Might explain how it occurs at a similiar point not in relation to RPM or gear.

 

very small vacuum leak ???... had similar issues in 89 FI honda

 

Well I'm finally back in the company of my 4Runner (and my computer,) and I got a chance to look atthe plugs, wires and distro, They all *look* fine. I wish I had the cash to just run through all of that stuff and replace it like I should, but right now I kinda need to pinpoint it if I can. The whole deal with it only happening at ~2500 rpm or when I down shift has me all kinds of bafflled. I havn't run through all my vaccum hoses yet, its freakin cold outside. Anyone else have any ideas?

 

im dealing with the SAME EXACT PROBLEM but i have the 3.0 3vze you should read my thread there is no usefull info in there yet. i just replaced my timing belt and 3 days later this started to happen exactly at 2500 or under hard accelleration the motor has a bad studder/miss. i had a mechanic hook it up to a diagnosis cpu and its had codes for the knock sensor and teh tps. i read that teh knock sensor wire can have a dirty connection thats the only thing i have come up with so far

 

Had the same problem , and it was the TPS sensor.

https://www.yotatech.com/forums/f116/gap-between-1800-2300-rpm-tps-problem-109638/

I adjusted to the specifications , following 4crawler description, now everything is fine.

You find here :
http://www.4crawler.com/4x4/CheapTricks/TPS/index.shtml


Zoli

 

You know you are going to have to spend some money, but the first thing to invest in is an inexpensive digital mulitmeter.....that is, if you are going to own and diagnose you're own EFI vehicle. Since it's an electronically controlled vehicle, the meter will be the way to troubleshoot the systems.

Get a meter (Harbor Freight, Lowe's, Home Depot) and feeler guage and test your throttle sensor. The symptoms you describe sound exactly like a TPS related problem. Go to the link (4crawler) Zozoka provided and follow the instructions for testing it paying attention to this...

"One final test, not listed in the FSM, would be to run the TPS shaft from idle to WOT and watch the VTA-E2 resistance and make sure it increases monotonically, no drop outs or dead spots. If you observe abrupt resistance changes, the TPS could have a burned area on one of the current tracks."

I suspect you'll find you're problem there.

 

I would suspect the EGR valve myself. I had the same problem and I ended up blocking mine off. A simple test would be to disconnect and plug the vacuum lines that actuate the EGR valve, Should take you about 5 mins. Go for a short drive you should be able to tell if it made a difference.

 

hey check your grounds!!!!!! thats what teh problem was on my beast. my ground cable had a plastic connector on it and the snap on teh connector was broken. so every timei would hit a big bump that little piece would back itelf out.

 

something to consider.

If there is no power lose, only a small dip in RPM's and still, a steady acceleration under moderate to heavy throttle, it is probably just the torque converter. My truck does this a lot right around 40 MPH under decent throttle. I only hear the difference, I do not feel it. The engine is still pulling, just the torque converter locks.

 

before you start looking into major problems, check the VAF, Vane Air Flow meter. since its a potentiometer with actual contacts, it can get corrosion and cause a dead spot when the engine 'sees' no air coming in. you can check it with a multimeter by by sweeping through closed and wide open throttle, voltage should increase with throttle. good luck

 

I'm having the same exact symptoms in my son's '90 3.0L. Poor gas milage, 11 in the city!, but runs fine and has the dead spot at 1800 rpm. So via this forum, I've found a faulty TPS(casing coming off and loose). Ohm meter verified burnt spot. Also thought it ia good idea to replace O2 sensor. This weekends project. Will have to look into the cat also.
208k on the original. Has had an engine swap with new head gaskets.
Autozone had the TPS part as TPS433. I thought, aftermarket, well ok, then when I got the part, it was DENSO!!! via Wells. Just under 90 bucks!! Yes!! Denso to me means an OE part. made in Japan for allot less. Got lucky there. Got the Bosch O2 sensor uni where you have to splice it in but looks very straight forward. Look forward to retiming, getting a better fuel mixture and maybe 16mpg city?
Symptoms via code's were knock sensor and EGR!